Rapid and accurate acoustic testing of microphones or microphone assemblies such as miniature ECM or MEMS microphone assemblies is of continued interest to manufacturers of portable communication devices such as mobile phones. It is essential to verify that incoming microphone assemblies are both 100% functional and comply with prescribed electroacoustic test limits or standards before being mounted in the mobile phones or other portable communication equipment.
A microphone test stand performing such acoustic testing should be capable of delivering accurate, fast and reliable measurements under varying environmental conditions such as varying temperature, humidity and atmospheric pressure. It is furthermore advantageous if the microphone test stand in a simple manner can be adapted to different physical geometries of the microphone assemblies. For certain types of miniature microphone assemblies, it is also important to avoid any application of mechanical force or pressure to the microphone capsule or module during acoustic testing to obtain correct test results. It is further advantageous if the microphone assembly is completely surrounded by an applied test sound pressure inside an acoustical chamber of the microphone test stand, e.g. such that the test sound pressure is applied both frontal and rear sides of the microphone assembly.
To enable a large throughput of tested microphone assemblies it would further be beneficial if the microphone test stand comprises a microphone holder which can be transported between first position outside the acoustical chamber with an exposed state of the microphone holder and a second position inside the acoustical chamber in shielded state of the microphone holder. This feature allows a test operator or technician to rapidly and safely place and orient the microphone assembly as intended in the microphone holder in the exposed state before the microphone assembly is transported into the sealed acoustic chamber where the acoustic testing is performed. Clearly, during the acoustic testing the microphone holder and assembly should both be placed inside the sealed or sound-proof acoustical chamber to be isolated from environmental noise.